Re: [Linux-cluster] Quorum disk over RAID software device

From: "Kaloyan Kovachev" <kkovachev varna net>

To: linux clustering <linux-cluster redhat com>

Subject: Re: [Linux-cluster] Quorum disk over RAID software device

Date: Wed, 16 Dec 2009 13:41:11 +0200

On Wed, 16 Dec 2009 01:02:19 +0100, Jakov Sosic wrote
> On Tue, 2009-12-15 at 19:51 +0100, Rafael [UTF-8?]MicГі Miranda wrote:
>
> >
[1]
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Logical_Volume_Manager_Administration/mirrored_volumes.html
> >
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Logical_Volume_Manager_Administration/mirvol_create_ex.html
>
> Thank you...
>
> This seems as a good replacement for DRBD, except that after one side of
> the mirror failse, whole logical volume would be synced from the start
> (because I presume there is no wfbitmap like in drbd)?
>
from [1] "An LVM mirror divides the device being copied into regions that are
typically 512KB in size. LVM maintains a small log which it uses to keep track
of which regions are in sync with the mirror or mirrors. This log can be kept
on disk, which will keep it persistent across reboots, or it can be maintained
in memory." - so they shouldn't be synced from start
About the 6 node cluster - do you really need to have it operational with just
a single node? If this is not mandatory it might be better to use different
votes for the nodes to break the tie instead of mirrored qdisk (one more place
for split brain) ... like 3 nodes with 2 votes and the others with 3 votes or
a combination with non mirrored qdisk (with 4 votes)
> --
> | Jakov Sosic | ICQ: 28410271 | PGP: 0x965CAE2D |
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